I think Flint is the perfect product to be AGPL licensed; the argument of "it could be a commercial product but we don't want it to be" holds a lot of weight.
To be fair: if you simply don't care about money, and just want to contribute to open source, there's an argument to be made that the AGPL is antisocial, since it prevents most other downstream projects from incorporating your work. I think reasonable people can disagree about this.
But if you care even a little bit about how your code fits into the marketplace, the AGPL is a fine choice, striking a balance between proprietary or restrictive licenses and "yes, please rape me" licenses like MIT.
That's not a knock against the BSD/MIT licenses. The 37s guys, who obviously care quite a bit about money, MIT-licensed Rails. They wanted maximal uptake. You have to consider your goals. We wanted to do some software development out in the open and work more closely with our users, but we didn't to fund competitors.
But 37s never opened any of their end products (basecamp, campfire etc), they open sourced the framework and for a framework BSD or LGPL makes more sense because nobody makes money directly from a framework or a library, they make money from the software built on top of it, this is why they are more likely to contribute their changes back. If you open source an end user product on the other hand, people are less likely to contribute back so AGPL is needed.
